1. Field of the Invention
The present invention relates to a plating apparatus and a plating liquid removing method, and more particularly to a plating apparatus useful for filling a metal such as copper into recesses for interconnects formed in a semiconductor substrate, and a method for removing plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, of a substrate holding member for use in the plating apparatus.
2. Description of the Related Art
Generally, aluminum or aluminum alloy has been used as a material for forming interconnect circuits on a surface of a semiconductor substrate. Higher integrated density on the semiconductor substrate requires that a material having a higher electric conductivity should be used for interconnect circuits. Therefore, there has been proposed a method comprising plating a surface of a substrate to fill interconnect patterns, formed in the substrate, with copper or a copper alloy.
Various methods such as chemical vapor deposition (CVD) process, sputtering process, and the like have been used to fill interconnect patterns, formed in a substrate, with copper or a copper alloy. However, when a metallic layer on a substrate is formed of copper or a copper alloy, i.e., when copper interconnects are formed on the substrate, the CVD process requires high cost, and, if an aspect ratio is high (i.e., a depth of the pattern is larger than a width thereof), then it is difficult to fill the interconnect patterns with copper or a copper alloy during a sputtering process. Therefore, the aforementioned plating method is most effective to fill interconnect patterns, formed in a substrate, with copper or a copper alloy.
There are various methods for plating a surface of a semiconductor substrate with copper. For example, in a cup-type plating method, a dip-type plating method, or the like, a plating tank always holds a plating liquid, and a substrate is dipped into the plating liquid. In another plating method, a plating tank holds a plating liquid only when a substrate is fed into a plating container. Further, in an electrolytic plating method, an electric potential difference is applied to plate a substrate. On the other hand, in an electroless plating method, an electric potential difference is not applied.
In cup-type plating apparatuses, a substrate is held by a substrate holding member with a peripheral edge and a back surface of the substrate being sealed, and plating is performed by contacting an exposed front surface of the substrate with a plating liquid. After this plating treatment, plating liquid is likely to remain on a substrate-contacting portion, or portions in its vicinity, of a substrate holding member. This remaining plating liquid, when dried, can produce undesired particles. Moreover, the remaining plating liquid can adhere to a subsequent substrate to be plated, leading to an insufficient plating of this substrate.
A method has been developed for removing such a plating liquid remaining on the substrate-contacting portion, or portions in its vicinity, of a substrate holding member. According to this method, a plating liquid removing device, having an absorbent for absorbing a plating liquid, or a sucking tool for sucking a plating liquid, is allowed to move in a circumferential direction along the substrate-contacting portion, or portions in its vicinity, of a substrate holding member so as to remove by absorption or suction plating liquid remaining on the substrate-contacting portion or portions in its vicinity.
The above conventional plating apparatuses that carry out this method, however, have the following drawbacks. The conventional apparatuses are so designed that the substrate holding member is fixed stationarily while the plating liquid removing device is allowed to rotate. This makes it impossible to conduct dewatering (spin-drying) of the substrate-contacting portion, or portions in its vicinity, of the substrate holding member. Since a large quantity of plating liquid thus remains, it is necessary to conduct a plating liquid removing operation for every plating treatment. Moreover, each plating liquid removing operation requires a considerably long time. Furthermore, removal of the large a quantity of plating liquid leads to consumption of an increased amount of plating liquid, resulting in an increased production cost.
The present invention has been made in view of the above drawbacks in the related art. It is therefore an object of the present invention to provide a plating apparatus and a plating liquid removing method which can easily and quickly remove plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, of a substrate holding member, and which allows for a simplified apparatus structure that requires a smaller space for installation.
According to a first aspect of the present invention, there is provided a plating apparatus, comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; a plating process container, disposed below the head, for holding a plating liquid therein; and a plating liquid removing mechanism for removing plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member.
The above apparatus can effectively remove the liquid remaining on the substrate-contacting portion, or portions in its vicinity, at the inner circumferential edge of the substrate holding member, forcibly. This can avoid a problem of particle generation that would be caused by unremoved plating liquid after it has dried. A possible dissolution of a seed layer of a subsequent substrate by unremoved plating liquid can also be avoided. Further, the above apparatus, which allows the substrate holding member to rotate, makes it possible to remove plating liquid and, in addition, eliminates a need to rotate the plating liquid removing mechanism.
In a preferred aspect of this invention, the plating liquid removing mechanism has a plating liquid suction nozzle which can move close to the substrate-contacting portion at the inner circumferential edge of the substrate holding member and suck plating liquid remaining on the substrate-contacting portion, or the portions in its vicinity.
The plating liquid suction nozzle may have an arc shape extending along the substrate-contacting portion of the substrate holding member, and may be designed to be movable in vertical and horizontal directions. Use of such a suction nozzle can carry out the of plating liquid remaining on the substrate-contacting portion, or the portions in its vicinity, efficiently in a short time.
In a preferred aspect of this invention, the plating liquid removing mechanism also has a cleaning liquid injection nozzle which can move close to the substrate-contacting portion at the inner circumferential edge of the substrate holding member and eject a cleaning liquid toward the substrate-contacting portion, or portions in its vicinity.
With this construction, the cleaning liquid injection nozzle ejects a cleaning liquid, e.g. pure water, toward the substrate-contacting portion, or the portions in its vicinity, at the inner circumferential edge of the substrate holding member, thereby cleaning the substrate-contacting portion, or the portions in its vicinity. Further, plating liquid remaining on the substrate-contacting portion, or the portions in its vicinity, is suction-removed, together with cleaning liquid, by the plating liquid suction nozzle. This can prevent plating liquid from remaining inside the plating liquid suction nozzle and clogging the nozzle after the liquid has dried.
According to a second aspect of this invention, there is provided a plating apparatus, comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; and a plating process container, disposed below the head, for holding a plating liquid therein; wherein the substrate holding member is provided with a sealing member for sealing an outer peripheral edge of the substrate, with the sealing member being made of a highly water-repellent material.
With this construction, the sealing member, which is to be contacted with the substrate, is made of a highly water-repellent material. This can reduce an amount of plating liquid that remains on a surface of the sealing member. Silicone rubbers may be used as the highly water-repellent material. Ordinary silicone rubbers, however, have a poor durability. In order to ensure a sufficiently high tensile strength, it is preferred to use a high-tearing strength silicone rubber having enhanced tensile strength. Use of such a specific rubber provides a sealing member having both a good sealing property and high durability.
According to a third aspect of this invention, there is provided a plating apparatus, comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; a plating process container, disposed below the head, for holding a plating liquid therein; and a plating liquid removing mechanism for removing a plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member; wherein the substrate holding member is provided with a sealing member for sealing an outer peripheral edge of the substrate, with the sealing member being made of a highly water-repellent material.
According to a fourth aspect of this invention, there is provided a plating apparatus, comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; and a plating process container, disposed below the head, for holding a plating liquid therein; wherein the substrate holding member is provided with a sealing member for sealing an outer peripheral edge of the substrate, with the sealing member having a substrate-contacting portion which is in a shape of a spire, in cross section, with a flat top surface.
With this construction, the specific configuration of the sealing member at the substrate-contacting portion can enhance rigidity of the substrate-contacting portion, and furthermore, and can cause plating liquid to remain on an inner side of the top flat surface, thereby not allowing the plating liquid to flow to an outer side (electrical contact side). This is advantageous because plating liquid, if flowed to the outer side, would not sufficiently be suction-removed and would still remain.
According to a fifth aspect of this invention, there is provided a plating apparatus, comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; a plating process container, disposed below the head, for holding a plating liquid therein; and a plating liquid removing mechanism for removing a plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member; wherein the substrate holding member is provided with a sealing member for sealing an outer peripheral edge of the substrate, with the sealing member having a substrate-contacting portion which is in a shape of a spire, in cross section, with a flat top surface.
According to a sixth aspect of this invention, there is provided a method for removing a plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of a substrate holding member for holding a substrate, comprising: rotating the substrate holding member to remove plating liquid from the substrate holding member; and sucking plating liquid remaining on the substrate-contacting portion, or portions in its vicinity, of the substrate holding member, while the substrate holding member is rotated.
According to a seventh aspect of this invention, there is provided a plating method, comprising: plating a substrate held by a substrate holding member of a rotatable housing; rotating the housing to remove a plating liquid remaining on the substrate and the substrate holding member; removing the substrate from the housing; and sucking plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member, while the substrate holding member is rotated.
According to an eighth aspect of this invention, there is provided a plating apparatus comprising: a head having a rotatable housing provided with a substrate holding member for holding a substrate; a plating process container, disposed below the head, for holding a plating liquid therein; and a plating liquid removing mechanism for removing a plating liquid remaining on a substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member; wherein the plating liquid removing mechanism has a plating liquid sucking member which is allowed to be introduced into the housing through an opening of the housing and to move near to the substrate holding member, with the plating liquid sucking member, when located so as to face the substrate holding member, sucking and removing plating liquid remaining on the substrate-contacting portion, or the portions in its vicinity, at inner circumferential edge of the substrate holding member, while the substrate holding member is rotated.
According to a ninth aspect of this invention, there is provided a plating method, comprising: plating a substrate held by a substrate holding member of a rotatable housing; rotating the housing to remove a plating liquid remaining on the substrate and the substrate holding member; removing the substrate from the housing through an opening of the; causing a plating liquid-sucking member of a plating liquid removing mechanism to face the substrate holding member by introducing the plating liquid removing mechanism into the housing through the opening; and removing plating liquid remaining on the substrate-contacting portion, or portions in its vicinity, at an inner circumferential edge of the substrate holding member in such a state that the plating liquid-sucking member closely faces the substrate holding member, while the substrate holding member is rotated.